Messages in this thread |  | | Subject | Re: [PATCH] lib/stackdepot: use a non-instrumented version of memcmp() | From | Andrey Ryabinin <> | Date | Thu, 16 Nov 2017 18:08:52 +0300 |
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On 11/15/2017 08:34 PM, Alexander Potapenko wrote: > stackdepot used to call memcmp(), which compiler tools normally > instrument, therefore every lookup used to unnecessarily call > instrumented code. > This is somewhat ok in the case of KASAN, but under KMSAN a lot of time > was spent in the instrumentation. > > Signed-off-by: Alexander Potapenko <glider@google.com> > --- > lib/stackdepot.c | 21 ++++++++++++++++++--- > 1 file changed, 18 insertions(+), 3 deletions(-) > > diff --git a/lib/stackdepot.c b/lib/stackdepot.c > index f87d138e9672..d372101e8dc2 100644 > --- a/lib/stackdepot.c > +++ b/lib/stackdepot.c > @@ -163,6 +163,23 @@ static inline u32 hash_stack(unsigned long *entries, unsigned int size) > STACK_HASH_SEED); > } > > +/* Use our own, non-instrumented version of memcmp(). > + * > + * We actually don't care about the order, just the equality. > + */ > +static inline > +int stackdepot_memcmp(const void *s1, const void *s2, unsigned int n) > +{
Why 'void *' types? The function treats s1, s2 as array of long, also 'n' is number of longs here.
> + unsigned long *u1 = (unsigned long *)s1; > + unsigned long *u2 = (unsigned long *)s2; > + > + for ( ; n-- ; u1++, u2++) { > + if (*u1 != *u2) > + return 1; > + } > + return 0; > +} > + > /* Find a stack that is equal to the one stored in entries in the hash */ > static inline struct stack_record *find_stack(struct stack_record *bucket, > unsigned long *entries, int size, > @@ -173,10 +190,8 @@ static inline struct stack_record *find_stack(struct stack_record *bucket, > for (found = bucket; found; found = found->next) { > if (found->hash == hash && > found->size == size && > - !memcmp(entries, found->entries, > - size * sizeof(unsigned long))) { > + !stackdepot_memcmp(entries, found->entries, size)) > return found; > - } > } > return NULL; > } >
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